The present invention relates to the field of pulley devices for tensioning or guide rollers provided to interact with a chain or a belt, for example a timing belt of a motor vehicle internal combustion engine.
Such rollers are usually used to maintain a tension at all times on the belt or the chain within a determined range or to locally modify the path taken by the latter. These are then called respectively tensioning rollers or guide rollers. In guide rollers, the pulley is mounted so as to rotate on a screw or a spindle by means of a rolling bearing, the roller then being attached directly or indirectly to the engine block or to an element of a tensioning roller device, for example an articulated arm or an eccentric.
In order to attach the roller to its support, a spacer is usually used in association with the said screw or spindle. During this mounting, it is desirable that the spindle or the screw is axially secured to the other elements forming the roller and comprising the pulley. This provides an inseparable assembly, that is easy to handle and transport and can be easily mounted.
For this purpose, document WO-A1-2007/036407 discloses a pulley device for a tensioning roller comprising a pulley, a rolling bearing, a flange capable of resting against an element outside the device, an attachment screw axially immobilized relative to the flange, and a friction ring provided between the flange and the screw. The flange described in this document does not make it possible to easily achieve the attachment of the device against the engine block.
Also known, through document DE-B4-100 03 208, is a pulley for a belt tensioning roller comprising a rolling bearing, a spacer for the mounting of the rolling bearing and an attachment screw axially immobilized relative to the spacer. The relative axial retention of the attachment screw and of the spacer is achieved by means of a continuous ring clamped onto a threaded portion of the attachment screw.
The major drawback of this solution is that it does not allow a particularly sure and effective retention of the attachment screw relative to the spacer. There is therefore a risk of accidental separation of the elements constituting the pulley device. Moreover, the operation of clamping the ring onto the threaded portion of the screw can be awkward to achieve.